family member of EU national applying for depandancy

hi to all

thank you for creating such a nice forum , my question is simple
i will be applying as a child of EU member (over 21) financially depandant on my parent , he is a retired self sufficient person and can show that
i just wanna know if some one had a similar situation and what is the steps?
should i show that me and my parent are living in the same flat with a joint tenancy agreement ?
my parent has a health insurance in another EU country which he currenlty reside and it is covering all the EU member states , will that be enough or should he get another fully comp health insurance?
also regarding bank statement , can we have a joint account for both or seperately ?
is it possible for them not to issue the RC as i am working part time and eran about 600 a month which is not enough to live by my own
had anyone had a similar sitaution and what happened ?
another silly question is what if after some time i find a full time job and start earning money ? can i still keep the RC or what ?!?